Integrated Life Cycle Assessment and Life Cycle Cost Assessment based fuzzy multi-criteria decision-making approach for selection of appropriate wastewater treatment system

The current study proposes a comprehensive fuzzy formulated Multi-Criteria Decision Making (MCDM) framework with integrated Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA) approach for selection of best suitable wastewater treatment (WWT) system, especially for multi-storeyed residential buildings. By utilising a thorough literature survey, experts' opinions and questionnaires, the study attempts to identify four dimensions of sustainability with associated key nineteen indicators. Furthermore, the study is benefited by undertaking quantitative parameters related to environmental and economic sustainability assessed by LCA and LCCA respectively. The proposed three-phase methodological framework illustrates the identification of widely used WWT systems in the first phase followed by Fuzzy Analytic Hierarchy Process (FAHP) assessment for criteria and indicators' screening and finalisation in the second phase and ranking of alternative by Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS) in the third phase. Moreover, the current paper suggests a novel approach of incorporating environmental floor in multi-storeyed building, where gravity governed nature-based wastewater treatment tanks of Decentralized On-Site Integrated WAste Management (DOSIWAM) system can be positioned. To test the proposed framework, the sustainability of DOSIWAM system is compared with five widely used wastewater treatment systems viz. membrane bioreactor (MBR), moving bed biofilm reactor (MBBR), sequencing batch reactors (SBR), activated sludge process (ASP), soil biotechnology (SBT). Results of alternative ranking indicate DOSIWAM (allocated at environmental floors) as the best suitable option followed by the second, third and fourth rank of MBR, SBT and SBR respectively whereas, MBBR and ASP are the least preferred. It has been observed that the experts prefer mostly natural treatment systems since they are more sustainable in environmental and economic considerations. In addition, by changing the weights of the main criteria, sensitivity analysis is carried out considering five scenarios, which signifies in three out of five scenarios; relative percentage change in criteria weight does not affect the first rank of the DOSIWAM system. The developed framework successfully facilitates a reliable base for the selection of the best suitable WWT system for multi-storeyed residential building and could be made available to the relevant local planning authority to incentivize the effort undertaken for the welfare of citizens as well as the government.

Automated summary

This study proposes a comprehensive fuzzy formulated Multi-Criteria Decision Making (MCDM) framework that integrates Life Cycle Assessment (LCA) and Life Cycle Cost Assessment (LCCA) approaches to select the best suitable wastewater treatment (WWT) system for multi-storeyed residential buildings. Through literature survey, expert opinions, and questionnaires, the study identifies four dimensions of sustainability and associated indicators. The framework uses LCA and LCCA to assess environmental and economic sustainability parameters. It consists of three phases: identification of WWT systems, screening of criteria and indicators using Fuzzy Analytic Hierarchy Process (FAHP), and ranking of alternatives using Fuzzy Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS). The study also suggests incorporating environmentally-friendly wastewater treatment tanks in multi-storeyed buildings. The proposed framework is tested by comparing the sustainability of the DOSIWAM system with other widely used WWT systems. The results show that DOSIWAM is the most suitable option, followed by MBR, SBT, SBR, MBBR, and ASP. Experts prefer natural treatment systems for their environmental and economic sustainability. Sensitivity analysis demonstrates the robustness of the DOSIWAM system. This framework provides a reliable basis for selecting the best WWT system for multi-storeyed residential buildings and can be used by local planning authorities to incentivize sustainable efforts.